Valve apparatus for deep drilling

ABSTRACT

A valve apparatus adapted for connection in a drill stem comprises a sleeve member slidably guided in a body having a longitudinal fluid passage and lateral openings that communicate with an annular space surrounding the sleeve member. The sleeve member also comprises lateral holes of small diameter and bottom orifices or channels of large diameter. In a first position of the sleeve member, the fluid flows from the drill stem towards the annular space through the holes of small diameter. When the rate of flow reaches a sufficient value, the sleeve member is moved against a biasing spring to a second position, where the small holes are closed and the large channels permit the passage of the fluid through the valve, towards the lower part of the drill stem, without any noticeable pressure drop. The sleeve member is retained in the said second position through the pressures in the drill stem and in the annular space acting on different areas of the sleeve member. When the pressure in the annular space suddenly increases, the sleeve member is moved to a third position wherein any communication between the drill stem and the annular space is avoided.

GENERAL DISCLOSURE

This invention relates, generally, to the technique of deep drilling ofthe ground.

This technique sometimes requires the use of devices ensuring the axialflow of circulation fluid injected into the drill stem, yet interruptingthis axial continuity and connecting the interior of the stem directlywith the exterior annular space when injection is broken off or when theflow descends below a certain minimum value.

This is the case, for instance, with release valves which are installedat a certain distance from the destruction tool, to ensure the fillingor emptying of the stem while running in or out of the hole or wherethere are obstacles to the free circulation of the fluid through devicessuch as an underground motor and in particular a volumetric motor or atool creating a high pressure loss.

The valves at present commercially available consist of an interiorsliding sleeve held in raised position by a spring which leaves openvents or channels connecting the interior of the stem with the annularexterior.

When circulation is established by injection of fluid into the drillstem, the sleeve, whose bore is narrow in relation to the normal passagesize, causes a loss of pressure and the resulting force compresses thespring, makes the sleeve descend and blocks the lateral passages to theannular section.

There are several serious disadvantages to this method of proceeding.Thus, the artificial loss of pressure created to cause the valve toclose constitutes a not negligible loss of energy which is costly andlast throughout the circulation. Furthermore, maintaining the axialchannel, below the valve, open does not prevent the penetration ofdrilling debris into the devices which the valve is in fact designed toprotect, thus risking their clogging. In addition, it is impossible toensure a circulation with low output but at high pressure through thedrilling tool, as may prove indispensable in case of instrumentation,for example following a jamming of the tool. Finally, the use of such avalve is incompatible with the presence of safety valves which drillersare generally required to install at the base of the drill stem whenthere is a risk of encountering eruptive strata.

One of the objects of the invention is to provide a release valveapparatus remedying the cited disadavantages.

Another object of the invention is to provide a release valve apparatuswhich may be adjusted, if desired, to fulfil the function of a safetyvalve.

Still another object of the invention is to provide a valve apparatusadapted for connection in a drill stem comprising a body having alongitudinal fluid passage and lateral openings communicating saidlongitudinal passage with the exterior of said body; a sleeve memberslidably mounted within said body between a first position in whichfluid may flow between an upper portion of said longitudinal passage andsaid lateral openings, and a second position in which said fluid isprevented to flow between said passage and said lateral openings, saidsleeve member being movable from said first to said second position inresponse to an increase of the flow from said passage to said lateralopenings above a predetermined flowrate; biasing means between said bodyand said sleeve member for urging said sleeve member towards said firstposition; valve means connected to said sleeve member for preventingflow of said fluid between upper and lower portions of said longitudinalpassage when said sleeve member is in said first position while allowingsubstantially unrestricted flow when said sleeve member is in saidsecond position; and piston means on said sleeve member sensitive to thedifference between the pressure in said passage and the pressure outsidesaid body when said sleeve member is in said second position formaintaining said sleeve member in said second position when saiddifference exceeds a predetermined value.

Another object of the invention is to provide a release valve apparatusto be mounted in a drilling stem, of the type comprising a casingprovided with threads linking with the stem and a sleeve movable betweenpositions of communication and non-communication between the interior ofthe stem and the external annular section and subject to the action of aspring or equivalent elastic means pulling it towards this position ofcommunication, characterised by the fact that the sleeve is in thegeneral form of a deep dish having a base acting as a part to block atrest the axial bore of the valve casing, the sleeve having in itslateral wall small diameter holes and, towards its base, passagechannels of large diameter, the sleeve also forming with the valvecasing a permanent communication chamber with the external annularsection. When the valve is at rest, the holes open into this chamber,and one part of the lateral wall of the sleeve can be positioned so asto cooperate with a part of the bore of the valve casing to isolatethese holes communicating with the external annular section and thus toavoid communication between the shaft and the annular section.

The sleeve can have a thicker part forming an annular surface at thelevel of the above-mentioned small diameter holes, and the bore of thevalve casing is fitted with a sealed joint with which this surface onthe sleeve may cooperate by sliding. It is obvious that this arrangementcould likewise be reversed if required, the joint being provided on thesleeve to cooperate with a surface or bearing on the valve casing.

According to another detail, when the valve is at rest, a part of thesleeve between the small diameter holes and the passage channels oflarge diameter is in contact with a sealing surface provided in the boreof the valve casing, such that the communication between the interior ofthe valve and the chamber itself in permanent communication with theexternal annular section is ensured solely through the small diameterholes.

When an increasing output of fluid is injected into the drill stem, thisfluid flows through these small diameter holes, creating at this point aloss of pressure. When the difference in pressures between the interiorof the valve and the exterior, resulting from the pressure loss thuscreated, reaches a sufficient value, it acts in the form of differentialpressures on the various parts of the section of the sleeve, theresultant of which tends to compress the spring, displacing the sleeveagainst the action of the spring. As a result of this sliding movement,the large diameter channels open freely into the lower part of the stem,so that an axial circulation is established practically without pressureloss, and the communication between the small diameter holes and theannular section is removed, the aforesaid sleeve being held in the lowposition by the differential pressure created by the pressure lossessuffered by the axial current below the valve.

According to another object of the invention, the base of the sleeve hasa push-valve normally held in place against this base by a spring orequivalent part, ensuring when at rest the sealed closure of the bore ofthe valve, at the foot of the sleeve. This push-valve may be separatedfrom the base by deforming the spring. According to a further detail, inthe chamber in permanent communication with the external annularsection, the sleeve forms a surface upon which the pressure in theannular section acts, this surface being directed downwards in thischamber so that excess pressure in the annular section such as thatproduced by an eruption at the bottom of the hole causes an upwardmovement of the sleeve by acting upon this surface, with resultingdeformation of the above-mentioned elastic part, the push-valveremaining in position against its seating to maintain a tight seal withthe part of the stem located below the valve. Means are provided toisolate the small diameter holes from the chamber in permanentcommunication with the external section, so that the inside of the valveis isolated from the external annular section and this valve thus actsas safety valve.

These means may comprise, for example, sealing surfaces providedrespectively on the sleeve and in the bore of the valve casing, thesesurfaces acting together when the sleeve is displaced upwards, toisolate these small diameter holes from the chamber in communicationwith the external annular section.

On the drawings:

FIG. 1 is a cross sectionnal view of a valve according to the invention,in resting position, that is in the absence of maintained injection inthe shaft.

FIG. 2 represents a half sectionnal view of the active part of the valveduring an injection.

FIG. 3 shows the valve functioning as safety valve.

Looking at FIG. 1, the reference 1 indicates the casing of the valve,the ends of which are provided with the usual threads 2, 3 for linkingwith the drill stem. It will be seen that this casing 1 is tubular inshape and is crossed by an axial bore indicated as a whole by thereference 4 and having sections of different diameter whose role will bedescribed in more detail later.

A part of the wall of the casing 1 has an annular strainer 5 of widedimension in order to reduce the risks of clogging. This strainerconnects the annular external section with a small chamber 6 whichitself communicates with the interior of the casing 1 via passages 7.

The sliding apparatus of the valve consists of a sleeve 8, the head 9 ofwhich is sealed in relation to the bore 4 of the casing 1 by a slidingseal ring 10, thus forming an annular chamber 11 in which is located aspring 12 resting upon a ring 13 which itself rests on a base plate 14.The latter has, on its side facing the wall of the bore 4 of the casing1 a stationary seal ring 15 and on the side facing the sleeve 8, twosliding seals 16 and 17.

The lower part of the sleeve 8 has a series of small diameter holes 18formed in a thick section 19 and a series of inclined channels orpassages 20 of large diameter formed in a base 21.

A bolt 22 screwed into the base 21 carries a spring 23 supported on theone hand by the head of the bolt and on the other hand by a push-valve24, in order to hold the latter against the base 21.

In the position shown in FIG. 1, the push-valve 24 is supported againsta shoulder 25 formed in the bore 4 of the casing 1 of the valve.

The operation of this valve will now be described.

FIG. 1 corresponds to the condition of the valve during manoeuvres, thatis while running the stem in and out. In this condition, the spring 12pushes the sleeve 8 upwards, the extent of movement being limited by thesealed abutment of the push-valve 24 against the shoulder 25. In thisposition, a free circulation of fluid is made possible between theinside of the stem and the external annular section via the bore 4, theholes 18, the chamber 11, the channels 7 and the strainer 5, thusallowing the filling and emptying of the stem.

On the other hand, the axial circulation of the fluid is interrupted onaccount of the closure of the push-valve 24.

When fluid is injected into the shaft, this fluid reaches the bore 4 andgoes through the holes 18 to the external annular section. As soon asthe differences of pressure caused by the loss of pressure created bythe flow of fluid through these holes 18 reaches a value at which theforce exerted on the section of the bore 4 exceeds the strength of thespring 12, this spring is compressed and the sleeve 8 moves down to theposition shown in FIG. 2, where the holes 18 are below the seal 16,whilst the channels open into the widest diameter section 26 of the bore4.

The valve remains in this position throughout the circulation, withoutparticular pressure loss in the circulation fluid current, under theinfluence of the differential pressures created by the pressure drop ofthe fluid current below the valve, before it reaches the externalannular section, the said pressure acting on different areas of thesleeve cross-section.

If an eruption occurs in the hole during running the drill stem in orout, that is when the valve is in the position shown in FIG. 1, theresult is a high pressure increase which is acting, inside the stem, onthe push-valve 24. On the other hand this pressure is transmitted by theannular section, so that the pressure in this part is greater than thepressure inside the stem, above the push-valve 24, and the fluidconsequently tends to pass from this annular section towards the insideof this stem, through the holes 18. If the pressure difference causedbetween the outside and the inside by pressure loss due to flow of fluidthrough these holes 18, which acts on the head 9 of the sleeve 8 fromthe chamber 11, is sufficiently high, it causes this sleeve to moveupwards by compression of the spring 23, to the position shown in FIG.3. It will be seen that, in this condition, the annular surface 27 ofthe sleeve 8 co-operates with the seal 17 to isolate the holes 18 fromthe annular external section, by closing the passage normally providedbetween the sleeve and the seal 17.

Thus, the inside of the stem is isolated from the annular section, onthe one hand where this annular surface 27 acts against the seal 17, andon the other hand by the push-valve 24.

If an excess pressure occurs whilst the valve is in the position shownin FIG. 2, and if this excess pressure is of sufficient value incomparison with the injection pressure of the circulation fluid, thevalve is then brought into the position shown in FIG. 1, and the samephenomenon as previously described occurs to bring the valve into theposition indicated in FIG. 3, where it acts as a safety valve.

It will be noted that, account being taken of the operating methoddescribed above, it is possible at any time to inject fluid at highpressure either through the holes 18, or in the position shown in FIG. 2by the axial channel, according to the output. Should the output offluid injected be insufficient to cause the sleeve 8 of the valve todescend by the normal action of pressures, it will nevertheless bepossible to open this valve by creating an additional pressure lossinside the sleeve, for example by dropping in a certain number of metalballs which would increase the resistance to the passage of the fluidwithout blocking the channels, thus causing the sleeve 8 to descend tothe position shown in FIG. 2.

What is claimed is:
 1. A valve apparatus adapted for connection in adrill stem comprising a body having a longitudinal fluid passage andlateral openings communicating said longitudinal passage with theexterior of said body; a sleeve member slidably mounted within said bodybetween a first position in which fluid may flow between an upperportion of said longitudinal passage and said lateral openings, and asecond position in which said fluid is prevented to flow between saidpassage and said lateral openings, said sleeve member being movable fromsaid first to said second position in response to an increase of theflow from said passage to said lateral openings above a predeterminedflowrate; biasing means between said body and said sleeve member forurging said sleeve member towards said first position; valve meansconnected to said sleeve member for preventing flow of said fluidbetween upper and lower portions of said longitudinal passage when saidsleeve member is in said first position while allowing substantiallyunrestricted flow when said sleeve member is in said second position;and piston means on said sleeve member sensitive to the differencebetween the pressure in said passage and the pressure outside said bodywhen said sleeve member is in said second position for maintaining saidsleeve member in said second position when said difference exceeds apredetermined value.
 2. The valve apparatus of claim 1 wherein saidpiston means comprise enlarged and reduced diameter external surfaces onsaid sleeve member slidably and sealingly engaging correspondinginternal surfaces of said body above and below said lateral openingsrespectively when said sleeve member is in said second position.
 3. Thevalve apparatus of claim 1 further including flow restriction meansthrough said sleeve member between said longitudinal passage and saidlateral openings when said sleeve member is in said first position forgenerating a pressure drop when the flow in said passage increases abovesaid predetermined flowrate to apply a force overcoming said biasingmeans to said sleeve member thereby displacing said sleeve membertowards said second position.
 4. A valve apparatus adapted forconnection in a drill stem comprising a body having a longitudinal fluidpassage and lateral openings communicating said longitudinal passagewith the exterior of said body; a sleeve member slidably mounted withinsaid body between a first position in which fluid may flow between saidpassage and said lateral openings, and second and third positions belowand above said first position in which the fluid is prevented to flowbetween said passage and said lateral openings, said sleeve member beingmovable from said first position to said second position in response toan increase of flow from said passage to said openings above apredetermined flowrate and from said first to said third position inresponse to an increase of flow from said openings to said passage aboveanother predetermined flowrate; biasing means between said body and saidsleeve member for urging said sleeve member to said first position;valve means connected to said sleeve member for preventing flow of fuidbetween upper and lower portions of said passage when said sleeve memberis in said first and third positions while allowing substantiallyunrestricted flow through said passage when said sleeve member is insaid second position; and, piston means on said sleeve member, sensitiveto the difference of pressures in said passage and outside said bodywhen said sleeve member is in said second and third positions formaintaining said sleeve member in said second position when the pressurein said passage less the pressure outside the body exceeds apredetermined value and for maintaining said sleeve member in said thirdposition when the pressure outside the body less the pressure in saidpassage exceeds a predetermined value.
 5. A valve apparatus adapted tobe connected in a drill stem, comprising a casing, means provided onsaid casing for connecting said valve apparatus to the drill stem, asleeve member movable between a first position wherein the inner passageof the drill stem is in communication with the annular space of the borehole, and a second position wherein said communication is blocked,spring means biasing said sleeve member towards said first position,said sleeve member having the shape of a deep dish comprising a base anda side wall, holes of small diameter provided in said side wall, nearsaid base, passages of large diameter provided in said base, acommunication chamber arranged between said sleeve and said valve casingand communicating with said annular space, said small holescommunicating between the interior of the sleeve member and saidcommunication chamber in said first position, said spring means beinglocated within said communication chamber, valve means connected to saidsleeve member for preventing flow of said fluid through said passages oflarge diameter when said sleeve member is in said first position,sealing means in contact with said sleeve member for preventing saidcommunication between the inner passage of the drill stem and saidannular space of the bore hole when said sleeve member is in said secondposition, and pressure reactive surfaces provided on said sleeve, saidsurfaces being directed upwardly and downwardly respectively and beingexposed to the inner part of said drill stem and to said communicationchamber respectively.
 6. A valve apparatus according to claim 5,comprising a first sealing surface provided on said sleeve member and asecond sealing surface provided on said valve casing, whereby in saidfirst position said holes of small diameter are open to saidcommunication chamber and said passages of large diameter are closed,while in said second position said first and second sealing surfaces arein contact with each other and isolate said holes of small diameter fromsaid communication chamber, while said passages are open to said drillstem below said valve apparatus.
 7. A valve apparatus according to claim5, comprising a first sealing surface provided on said sleeve memberabove said holes of small diameter and a second sealing surface providedon said valve casing, whereby in said second position of said sleevemember said first sealing surface rests upon said second sealing surfaceto isolate said holes of small diameter from said communication chamber.8. A valve apparatus according to claim 5, comprising a first sealingsurface provided on said sleeve member above said holes of smalldiameter and a second sealing surface provided on said valve casing, apush-valve arranged under said base of said sleeve member and movablewith respect thereto, spring means biasing said push-valve against saidbase, and a seat provided on said valve casing, whereby in said firstposition of said sleeve said push-valve rests against said seat to blockthe communication between the upper and lower parts of said drill stemthrough said passages, and in the second position of said sleeve saidfirst sealing surface rests against said second sealing surface toisolate said holes of small diameter from said communication chamber,and said push-valve is spaced from said seat through said base of saidsleeve member to permit free flow of the fluid from the upper part tothe lower part of said drill stem through said passages.
 9. A valveapparatus according to claim 5, wherein said dish shaped sleevecomprises an upper flange part, an upwardly directed surface provided onsaid flange part and submitted to the pressure in the drill stem, adownwardly directed surface provided on said flange, in communicationwith said communication chamber and said annular space, said springmeans resting upon said downwardly directed flange surface, and sealingmeans provided in said flange part and resting against the inner wallsurface of said valve casing.
 10. A valve apparatus according to claim5, comprising a push-valve provided under the base of said dish shapedsleeve member, a seat provided on said valve casing, spring meansnormally pressing said push-valve against said seat and said sleevebase, said push-valve being spaced from said valve casing seat in saidsecond position of said sleeve while resting against said base, toprovide a communication between the parts of the drill stem locatedabove and below said valve apparatus, through said passages, said sleevebeing movable to a third upper position wherein said push valve restsagainst said valve casing seat and said base is spaced upwardly fromsaid push valve, and a third sealing surface provided on the inner wallof said valve casing, said first sealing surface of said sleeve restingagainst said third sealing surface in said third position of saidsleeve, to isolate said holes of small diameter from said communicationchamber and to block any communication between the upper part of saiddrill stem and the lower part of said drill stem through said push valveresting against said seat.